CuCo2O4 Hollow Microspheres with Graphene Composite Targeting Superior Lithium-Ion Storage.

CuCo2O4, a type of promising lithium-ion storage material, exhibits high electrochemical properties in lithium-ion batteries and enormous economic benefits. However, its practical application is limited by problems such as structural collapse and electrochemical stability during the charging and discharging process. In this work, the reduced graphene oxide (rGO)-coated CuCo2O4 (CuCo2O4/rGO) hollow microspheres were successfully prepared by electrostatic self-assembly. The CuCo2O4/rGO electrode shows an outstanding capability for lithium-ion storage and a remarkable rate capacity, e.g., 445 mA h g-1 at 5 A g-1. After 150 cycles at 0.1 A g-1, the reversible capacity of the CuCo2O4/rGO electrode is as high as 1080 mA h g-1, and it can still retain about 530 mA h g-1 in the 400th cycle at 1 A g-1. The hollow microspheres with mesoporous shells can cause electrolyte penetration into the spherical shell to effectively shorten the transfer distance of lithium ions, and the encapsulation of graphene improves the conductivity and stability of CuCo2O4, which endows CuCo2O4/rGO with a wonderful Li+ storage performance. It is proved that this is an efficient method to improve the electrochemical performance of metal compounds for better applications in energy storage.